The primary goal of this project is an understanding of collagen structure from the molecular to the fibril level. Emphasis us presently on conventional and scanning transmission electron microcsopy and analysis of micrographs to obtain quantitative data and reveal detail not obvious to the eye. Two types of specimen are being examined. One is negatively stained aggregates of collagen by conventional electron microscopy. The second is unstained aggregates of collagen by scanning transmission electron microscopy. Collaborative studies are also in progress using specifically heavy metal staine collagen samples by scanning transmission electron microscopy. The image processing techniques developed for this project have been shown to be generally applicable.